Scope: We are the connections team and our mission is to design piping for the transportation of gaseous hydrogen from storage to compressor.
Goal: Connect the compressor to an external H2 source, the buffer storage system, and a hydrogen return line (from cooling system).
High-Temperature Syngas & Low-Temperature Liquid Hydrogen
We started off by finding materials to contain and transport the syngas from AgEnergy and the liquid hydrogen with which our system would be interacting. This presented us with a challenge, because the syngas was estimated to be entering our system at 400 degrees Celsius and hydrogen doesn’t liquefy above 33 K. With that in mind, we came up with three materials, with the possibility of using a combination of them: carbon steels, microalloyed steels, and fiber-reinforced polymers. Carbon steels, being the most common, would be the cheapest option, however it would suffer from hydrogen embrittlement, a phenomenon you can find more information here. Microalloyed steels, more specifically stainless steel 316L, would be able to cover the full range of temperatures. In addition, it would be strong because it is also classified as a high-strength, low-alloy steel. The advantage of this material is that we would have just one pipe material throughout the system, however, this would be more expensive. Fiber-reinforced polymers would ensure minimal leakage of the liquid hydrogen. The low melting temperature of the material would mean it could not be used to transport the syngas.
Liquid Hydrogen Connections
Next, we shifted our attention to the liquid hydrogen connections. Hydrogen, being the smallest element, is so small that an atom of hydrogen is about 3.7 times smaller than a water molecule. That’s like comparing a raquetball to a bowling ball. For these connections: we came up with two types: Bayonet and VCR connections. Bayonet connections are named after the way a bayonet is attached to a musket, which is by pushing down and then turning one end in place. Like the soldiers who were untrained and had a quick way to attach their bayonet, we would have a just-as-easy connection with our liquid hydrogen in addition to it being leak-tight. The VCR connections would also be leak-tight. They involve multiple components that work to tighten together. Because there are multiple components, the cost would be higher.
High-Pressure, Gaseous Hydrogen
Finally, we focused on the transport of gaseous hydrogen throughout our system. We decided to go with compression connections because of they are cheap, off-the-shelf, and they require less components.We realized that we would need to come up with a layout that could satisfy our goal of connecting an external hydrogen source to the compressor, the buffer system as needed and feed the compressed hydrogen to the liquefaction and purification processes, using the buffer system as just that: a buffer. To this end, we came up with a system diagram that maps out our system and gives a schematic for the essential components, which include automated pressure valves, a pressure regulator, and check valves. The System Diagram is shown below on the left, and the corresponding CAD model is on the right.
Update: Moving forward, we might also have to provide a line from the buffer tanks to a hydrogen fuel cell. The purpose of this fuel cell would be, in case of an emergency power outage, it would slowly utilize the hydrogen gas in the tanks and lines to run the ventilation and sensing components of our system for at least 24 hours. This way, when the fuel cell runs out of fuel, there would be little to no hydrogen in the lines, so the ventilation and sensing would no longer be required.
By our judgement, this change would only add some tubing, a pressure regulator, and possibly some connectors, and would not change the overall schematic of our system.
For our system, we will need a variety of materials. We will need:
These components are in compliance with the safety standard ASME sections B16.5, B31.12, B31.3, B31.8, and Y14.5. As evident from the table above, the total cost of this part of the project will amount to about $6,019.
As the project comes to completion, we will be working with these teams to ensure a smooth installation:
- System Integration Team:
We will be working with System Integration to finalize the layout of the container, and get more precise measurements as the rubber meets the road and theory becomes reality during installation.
- Storage/Compressor Teams:
We will be working with these teams to provide proper connections between our piping and their component.
- Leak Detection Team:
We will be working with this team to ensure minimal leakage to prevent 0.6% hydrogen in the air.